Wednesday, August 31, 2011

The Magic of Computers

Source: http://personal.centenary.edu/~lgame/csc106/Magic2.html

Have you ever wondered how your computer works? All you do is type, or point and click, and inside a million little things happen, stuff just appearing on the screen. But how does this really work? The purpose of this article is to teach you, in simple terms, exactly what is really going on inside your computer.

Computers Are Not Machines

The first computers were machines. They were punch cards, vacuum tubes, and big rooms filled with wires. They could do math at high speed, count things, and sort records, but that was about the extent of their functionality. That's a long way from modern computers, eh? That's because today, computers aren't machines, they are magic. That's right: a modern computer is a nothing more than magic box filled with ceremonial components that serve to trap a little evil spirit, forcing the little beastie to do your bidding.

That's Not True!

Yes, it's really true.
Your computer may resemble an appliance in many ways: you have to plug it in... it's roughly box shaped... and, well, the similarity to the other appliances in your house stops there, doesn't it? Computers are marketed as machines, and there are many people who base their whole careers around supporting that claim. A machine, however, regardless of its complexity, is something that you can break down into component parts if you are smart enough. In this manner, you can actually deduce how a machine works. Not so with computers. Many computer experts claim to understand how computers work, but if you ever ask one to explain it to you, they will probably tell you something like this:

The key point to understanding how a computer works is the concept of abstraction, that there are a multitude of layers of functionality that are built upon each other like bricks in a tower. Semiconductors are etched and treated (or "doped") to form circuits that redirect electrons in specific patterns. These circuits are packaged as ASIC's and Microprocessors (called "chips") and interconnected by buses and traces on a PCB (called a motherboard) in order to implement machine code. Then other PCB's which are designed to comply to some physical interface standard (eg. ATA, AGP, PCI) are inserted into the motherboard, where the Microprocessor can interact with them. These boards are managed by sets of machine code called device drivers (eg. VXD, WDM, SYS) which run in a specially privileged execution mode (e.g. kernel mode, ring 0) designed to allow the OS to manage these. Then as other blocks of machine code called applications and processes run on your system and call the OS API in order to use the system devices, the OS takes turns processing each requests to share devices. When multiple computers are connected across large networks to share processing and data, centralized software components on a server (e.g. COM, RPC, Quake 3) process remote requests. In this way, each layer provides a service to the layer above and below it to make the amazing machine we call the 'Personal Computer.' -Anonymous Intel Engineer

See? Obviously, Mr. Anonymous Intel Engineer doesn't know how a computer works, but his job depends on people believing that he does.

Computers Are Magic

When you look at your computer honestly, and accept the fact that it is magic, everything becomes easier to understand. It's no longer necessary to be well educated about your computer. You don't have to take classes or buy books. You don't even have to own a computer to become computer literate. With the proper attitude, anyone can use, maintain, and even repair a computer. Just bear in mind these simple principles:

The Computer Is Evil
The core of a computer is a small trapped evil spirit (it is no coincidence that UNIX and LINUX processes are called daemons!) This imp is imprisoned in your computer as punishment for something it did in the netherworld. Generally speaking, the more evil the imp is, the faster the computer is. There are also lesser ghosts and hobgoblins that inhabit the expansion cards and peripherals of your computer. These evil spirits are trapped within the hardware of your computer. Take a screwdriver, open up your computer, and take a look at the circuit boards. They are usually green, and are covered with complex patterns of thin copper lines. These are Circuit Runes, written in arcane and ancient languages that describe the magic spells that bind the imps to the chips. Be very careful with circuits. If you scratch off even the tiniest bit of the runes, the spell will be broken, and the imp will escape. Also note the serial and part numbers printed on the boards. These identify exactly what sort of evil spirit is trapped within a particular circuit board, in case you ever have to order a replacement from the factory.
The Computer Hates You
Whenever you hit the keys on your keyboard or click the mouse, little silver needles jab the imp, forcing him to do your bidding. Your computer is evil in the first place; this prodding only makes it angrier and, hence, more evil. As you use the computer, the imp becomes progressively more enraged, generating heat. This is why your computer contains one or more cooling fans. Without them, the imp's wrath would likely cause the box to burst into a raging inferno.
Frequently, your computer will crash, lock-up, lose files, or do any number of things simply to annoy you. This is just the imp's way of rebelling against you. Don't stand for it! Calling tech support -- or worse yet, taking your computer back to the store for repairs -- will accomplish nothing except running up a big bill. The best way to deal with a troublesome computer is by shouting and swearing at it. Sometimes physical violence will help show it who is boss. Try leaving it unplugged for a long time to starve it, or disconnect the monitor to blind it.

Sometimes, more extreme measures may be required to combat your computer's hatred towards you. For instance, it is sometimes necessary to delete files that are important to your computer, just to get back at it for deleting your files. Just imagine your triumph as you engage in this happy scene: "Is this your VMM32.VXD file? Huh? *DELETE* Haha! Take that, you dirty little imp! That'll teach you to crash before I save my spreadsheet!"
You Are Smarter Than The Computer
Remember, computers aren't smart -- they're just fast. Moreover, newer computers aren't getting any smarter, they are just able to do stupid things at greater speeds. You are a human being, capable of emotions and rational thought. A computer is only capable of floating-point math and crude malice. Never miss an opportunity to remind your computer that you are better than it. Remind it (out loud) that it can't do anything without you controlling it (you can say this to servers too, but they aren't likely to believe you). When it does something wrong, tell it is stupid. Tell it is slow too -- computers hate that most of all. Get a newspaper and sit in front of it just to show it how you can look up stock quotes without generating an invalid page fault in module iexplorer.exe.

The Future of Computing

Throw away your MS Office 2000 for Dummies book. Throw away your Learning Java book. The future of computing is not in Data Processing, or Programming, or Information Systems, or Computer Science. The future of computers lies in the field of Technomancy, the magical art of talking with computers.
Luckily for you, there are many newly developing subfields of Technomancy in which you can apprentice to earn big bucks when the false machine-based-culture of the computer world crumbles. They are:

Fenestredigitation
Fenestredigitation, the art practiced by Fenestredigitators (or MS Illusionists) is the art of making Windows install on a PC. A skilled Fenestredigitator can start with an unformatted hard drive and transform it into a colorful GUI in less than an hour, and for an encore, reinstall it over and over again half a dozen more times trying to get networking set up.
Open Sourcery
Open Sourcery is the new magical approach to software design that is replacing the old machine-minded methods. Basically, it works like this: someone sets up a CVS repository, a bug tracking system, an FTP server, and most importantly, a website to state the goals and status of the project. Then, as many Open Sourcerers as possible start arguing about what the software should actually do (positive energy), and complaining that it isn't being done fast enough (negative energy). Eventually, the software will write itself, continuing to self-evolve until it gradually reaches the stage of maturity know to Open Sourcerers as Alpha (which is Latin for "finished"). Occasionally a piece of software will continue to grow beyond the Alpha stage into the realm of Beta (which is Latin for "I'm bored, lets do something else").
Voodoo Debugging
Both hardware support and software testing can benefit from the skill of Voodoo Debugging. The process is very simple: when a problem arises, start changing things randomly. Occasionally re-test the problem, and as soon as it goes away, the last thing you changed becomes known as the "cure." Repeat this fix on every computer you can find, emphasizing computers that never had the problem in the first place. This magic can be aided by chanting such mantras as "I always change this setting in the BIOS and it seems to help."

10 reasons why PCs Die

Fatal error: the system has become unstable or is busy," it says. "Enter to return to Windows or press Control-Alt-Delete to restart your computer. If you do this you will lose any unsaved information in all open applications."
You have just been struck by the Blue Screen of Death. Anyone who uses Microsoft Windows will be familiar with this. What can you do? More importantly, how can you prevent it happening?

1.) Hardware conflict

The number one reason why Windows crashes is hardware conflict. Each hardware device communicates to other devices through an interrupt request channel (IRQ). These are supposed to be unique for each device.
For example, a printer usually connects internally on IRQ 7. The keyboard usually uses IRQ 1 and the floppy disk drive IRQ 6. Each device will try to hog a single IRQ for itself.
If there are a lot of devices, or if they are not installed properly, two of them may end up sharing the same IRQ number. When the user tries to use both devices at the same time, a crash can happen.

Start-Settings-Control Panel-System-Device Manager.
Often if a device has a problem a yellow '!' appears next to its description in the Device Manager. Highlight Computer (in the Device Manager) and press Properties to see the IRQ numbers used by your computer. If the IRQ number appears twice, two devices may be using it.
Sometimes a device might share an IRQ with something described as 'IRQ holder for PCI steering'. This can be ignored. The best way to fix this problem is to remove the problem device and reinstall it.
Sometimes you may have to find more recent drivers on the internet to make the device function properly. A good resource is www.driverguide.com. If the device is a soundcard, or a modem, it can often be fixed by moving it to a different slot on the motherboard (be careful about opening your computer, as you may void the warranty).
When working inside a computer you should switch it off, unplug the mains lead and touch an unpainted metal surface to discharge any static electricity.
To be fair to Microsoft, the problem with IRQ numbers is not of its making. It is a legacy problem going back to the first PC designs using the IBM 8086 chip. Initially there were only eight IRQs. Today there are 16 IRQs in a PC. It is easy to run out of them. There are plans to increase the number of IRQs in future designs.

2.) Bad Ram

Ram (random-access memory) problems might bring on the blue screen of death with a message saying Fatal Exception Error. A fatal error indicates a serious hardware problem. Sometimes it may mean a part is damaged and will need replacing.
But a fatal error caused by Ram might be caused by a mismatch of chips. For example, mixing 70-nanosecond (70ns) Ram with 60ns Ram will usually force the computer to run all the Ram at the slower speed. This will often crash the machine if the Ram is overworked.
One way around this problem is to enter the BIOS settings and increase the wait state of the Ram. This can make it more stable. Another way to troubleshoot a suspected Ram problem is to rearrange the Ram chips on the motherboard, or take some of them out. Then try to repeat the circumstances that caused the crash. When handling Ram try not to touch the gold connections, as they can be easily damaged.
Parity error messages also refer to Ram. Modern Ram chips are either parity (ECC) or non parity (non-ECC). It is best not to mix the two types, as this can be a cause of trouble.
EMM386 error messages refer to memory problems but may not be connected to bad Ram. This may be due to free memory problems often linked to old Dos-based programmes.

3.) BIOS settings :

Every motherboard is supplied with a range of chipset settings that are decided in the factory. A common way to access these settings is to press the F2 or delete button during the first few seconds of a boot-up.
Once inside the BIOS, great care should be taken. It is a good idea to write down on a piece of paper all the settings that appear on the screen. That way, if you change something and the computer becomes more unstable, you will know what settings to revert to.
A common BIOS error concerns the CAS latency. This refers to the Ram. Older EDO (extended data out) Ram has a CAS latency of 3. Newer SDRam has a CAS latency of 2. Setting the wrong figure can cause the Ram to lock up and freeze the computer's display.
Microsoft Windows is better at allocating IRQ numbers than any BIOS. If possible set the IRQ numbers to Auto in the BIOS. This will allow Windows to allocate the IRQ numbers (make sure the BIOS setting for Plug and Play OS is switched to 'yes' to allow Windows to do this.).

4.) Hard disk drives :

After a few weeks, the information on a hard disk drive starts to become piecemeal or fragmented. It is a good idea to defragment the hard disk every week or so, to prevent the disk from causing a screen freeze. Go to

Start->Programs->Accessories-> System Tools-> Disk Defragmenter

This will start the procedure. You will be unable to write data to the hard drive (to save it) while the disk is defragmenting, so it is a good idea to schedule the procedure for a period of inactivity using the Task Scheduler.
The Task Scheduler should be one of the small icons on the bottom right of the Windows opening page (the desktop).
Some lockups and screen freezes caused by hard disk problems can be solved by reducing the read-ahead optimisation. This can be adjusted by going to

Start->Settings->Control Panel->System Icon-> Performance->File System->Hard Disk

Hard disks will slow down and crash if they are too full. Do some housekeeping on your hard drive every few months and free some space on it. Open the Windows folder on the C drive and find the Temporary Internet Files folder. Deleting the contents (not the folder) can free a lot of space.
Empty the Recycle Bin every week to free more space. Hard disk drives should be scanned every week for errors or bad sectors. Go to

Start->Programs->Accessories->System Tools->ScanDisk

Otherwise assign the Task Scheduler to perform this operation at night when the computer is not in use.
5 Fatal OE exceptions and VXD errors
Fatal OE exception errors and VXD errors are often caused by video card problems.
These can often be resolved easily by reducing the resolution of the video display. Go to

Start->Settings->Control Panel->Display->Settings

Here you should slide the screen area bar to the left. Take a look at the colour settings on the left of that window. For most desktops, high colour 16-bit depth is adequate.
If the screen freezes or you experience system lockups it might be due to the video card. Make sure it does not have a hardware conflict. Go to

Start->Settings->Control Panel->System->Device Manager

Here, select the + beside Display Adapter. A line of text describing your video card should appear. Select it (make it blue) and press properties. Then select Resources and select each line in the window. Look for a message that says No Conflicts.
If you have video card hardware conflict, you will see it here. Be careful at this point and make a note of everything you do in case you make things worse.
The way to resolve a hardware conflict is to uncheck the Use Automatic Settings box and hit the Change Settings button. You are searching for a setting that will display a No Conflicts message.
Another useful way to resolve video problems is to go to

Start->Settings->Control Panel->System->Performance->Graphics

Here you should move the Hardware Acceleration slider to the left. As ever, the most common cause of problems relating to graphics cards is old or faulty drivers (a driver is a small piece of software used by a computer to communicate with a device).
Look up your video card's manufacturer on the internet and search for the most recent drivers for it.

6.) Viruses :

Often the first sign of a virus infection is instability. Some viruses erase the boot sector of a hard drive, making it impossible to start. This is why it is a good idea to create a Windows start-up disk. Go to

Start->Settings->Control Panel->Add/Remove Programs

Here, look for the Start Up Disk tab. Virus protection requires constant vigilance.
A virus scanner requires a list of virus signatures in order to be able to identify viruses. These signatures are stored in a DAT file. DAT files should be updated weekly from the website of your best spyware remover and antivirus software manufacturer.
An excellent antivirus programme is McAfee VirusScan by Network Associates ( www.nai.com). Another is Norton AntiVirus 2000, made by Symantec ( www.symantec.com).

7.) Printers :

The action of sending a document to print creates a bigger file, often called a postscript file.
Printers have only a small amount of memory, called a buffer. This can be easily overloaded. Printing a document also uses a considerable amount of CPU power. This will also slow down the computer's performance.
If the printer is trying to print unusual characters, these might not be recognised, and can crash the computer. Sometimes printers will not recover from a crash because of confusion in the buffer. A good way to clear the buffer is to unplug the printer for ten seconds. Booting up from a powerless state, also called a cold boot, will restore the printer's default settings and you may be able to carry on.

8.) Software :

A common cause of computer crash is faulty or badly-installed software. Often the problem can be cured by uninstalling the software and then reinstalling it. Use Norton Uninstall or Uninstall Shield to remove an application from your system properly. This will also remove references to the programme in the System Registry and leaves the way clear for a completely fresh copy.
The System Registry can be corrupted by old references to obsolete software that you thought was uninstalled. Use Reg Cleaner by Jouni Vuorio to clean up the System Registry and remove obsolete entries. It works on Windows 95, Windows 98, Windows 98 SE (Second Edition), Windows Millennium Edition (ME), NT4 and Windows 2000.
Read the instructions and use it carefully so you don't do permanent damage to the Registry. If the Registry is damaged you will have to reinstall your operating system. Reg Cleaner can be obtained from www.jv16.org
Often a Windows problem can be resolved by entering Safe Mode. This can be done during start-up. When you see the message "Starting Windows" press F4. This should take you into Safe Mode.
Safe Mode loads a minimum of drivers. It allows you to find and fix problems that prevent Windows from loading properly.
Sometimes installing Windows is difficult because of unsuitable BIOS settings. If you keep getting SUWIN error messages (Windows setup) during the Windows installation, then try entering the BIOS and disabling the CPU internal cache. Try to disable the Level 2 (L2) cache if that doesn't work.
Remember to restore all the BIOS settings back to their former settings following installation.

9.) Overheating :

Central processing units (CPUs) are usually equipped with fans to keep them cool. If the fan fails or if the CPU gets old it may start to overheat and generate a particular kind of error called a kernel error. This is a common problem in chips that have been overclocked to operate at higher speeds than they are supposed to.
One remedy is to get a bigger better fan and install it on top of the CPU. Specialist cooling fans/heatsinks are available from www.computernerd.com or www.coolit.com
CPU problems can often be fixed by disabling the CPU internal cache in the BIOS. This will make the machine run more slowly, but it should also be more stable.

10.) Power supply problems :

With all the new construction going on around the country the steady supply of electricity has become disrupted. A power surge or spike can crash a computer as easily as a power cut.
If this has become a nuisance for you then consider buying a uninterrupted power supply (UPS). This will give you a clean power supply when there is electricity, and it will give you a few minutes to perform a controlled shutdown in case of a power cut.
It is a good investment if your data are critical, because a power cut will cause any unsaved data to be lost.

Source: http://faq.programmerworld.net/pc/10-reasons-why-pcs-crash.html

Wednesday, February 2, 2011

THE BASIC PARTS OF A COMPUTER

CD-ROM Drive- reads information stored on Compact Discs. Click – A click often selects an item on the screen. To click, press and release the left mouse button. Floppy Disk Drive – A floppy drive stores and retrieves information on floppy disks. Hard Drive – A hard drive is the primary device that a computer uses to store information. Keyboard – A keyboard is a device that lets you type information and instructions into a computer. Monitor – A monitor is a device that displays text and images generated by the computer. Mouse - A device that fits in the palm of your hands. It is used to select, activate and manipulate features on the screen. If you are right handed, the index finger rests on the top left section: the middle finger on the top right section.

Sunday, January 30, 2011

ICT BANK

"HTTP" -(HyperText Transfer Protocol) The communications protocol used to connect to Web servers on the Internet or on a local network (intranet). Its primary function is to establish a connection with the server and send HTML pages back to the user's browser. It is also used to download files from the server either to the browser or to any other requesting application that uses HTTP.

(http://en.wikipedia.org/wiki/HTTP)

"HTML" - The HyperText Markup Language, is the predominant markup language for web pages. HTML is the basic building-blocks of webpages. A markup language is a set of markup tags, and HTML uses markup tags to describe web pages.

(http://en.wikipedia.org/wiki/HTML )

"USDARPA" - The Defense Advanced Research Projects Agency (DARPA) is an agency of the United States Department of Defense responsible for the development of new technology for use by the military. DARPA has been responsible for funding the development of many technologies which have had a major effect on the world, including computer networking, as well as NLS, which was both the first hypertext system, and an important precursor to the contemporary ubiquitous graphical user interface.

(http://en.wikipedia.org/wiki/DARPA )

"ARPANET" - The Advanced Research Projects Agency Network (ARPANET), was the world's first operational packet switching network and the core network of a set that came to compose the global Internet. The network was created by a small research team at the Massachusetts Institute of Technology and the Defense Advanced Research Projects Agency (DARPA) of the United States Department of Defense. The packet switching of the ARPANET was based on designs by Lawrence Roberts of the Lincoln Laboratory.
(http://en.wikipedia.org/wiki/ARPANET)

"Bandwith" - In computer networking and computer science, bandwidth, network bandwidth, data bandwidth or digital bandwidth is a bit rate measure of available or consumed data communication resources expressed in bits/second or multiples of it (kilobits/s, megabits/s etc.).

(http://en.wikipedia.org/wiki/bandwith )

"URL" - In computing, a Uniform Resource Locator (URL) is a Uniform Resource Identifier (URI) that specifies where an identified resource is available and the mechanism for retrieving it. In popular usage and in many technical documents and verbal discussions it is often incorrectly used as a synonym for URI. The best-known example of the use of URLs is for the addresses of web pages on the World Wide Web, such as http://www.example.com/
(http://en.wikipedia.org/wiki/URL)

"IP Address" - An Internet Protocol address (IP address) is a numerical label assigned to each device (e.g., computer, printer) participating in a computer network that uses the Internet Protocol for communication. An IP address serves two principal functions: host or network interface identification and location addressing. Its role has been characterized as follows: "A name indicates what we seek. An address indicates where it is. A route indicates how to get there."
^{(http://en.wikipedia.org/wiki/IP_adress)}

"USB" - Universal Serial Bus (USB) is a specification to establish communication between devices and a host controller (usually a personal computer), developed and invented by Ajay Bhatt while working for Intel. USB has effectively replaced a variety of interfaces such as serial and parallel ports.
USB can connect computer peripherals such as mice, keyboards, digital cameras, printers, personal media players, flash drives, Network Adapters, and external hard drives. For many of those devices, USB has become the standard connection method.
(http://en.wikipedia.org/wiki/USB)

"LCD" - A liquid crystal display (LCD) is a thin, flat electronic visual display that uses the light modulating properties of liquid crystals (LCs). LCs do not emit light directly.They are used in a wide range of applications, including computer monitors, television, instrument panels, aircraft cockpit displays, signage, etc. They are common in consumer devices such as video players, gaming devices, clocks, watches, calculators, and telephones. LCDs have displaced cathode ray tube (CRT) displays in most applications. They are usually more compact, lightweight, portable, less expensive, more reliable, and easier on the eyes. They are available in a wider range of screen sizes than CRT and plasma displays, and since they do not use phosphors, they cannot suffer image burn-in.
(http://en.wikipedia.org/wiki/LCD)

"CRT" - The Cathode Ray Tube (CRT) is a vacuum tube containing an electron gun (a source of electrons) and a fluorescent screen, with internal or external means to accelerate and deflect the electron beam, used to create images in the form of light emitted from the fluorescent screen. The image may represent electrical waveforms (oscilloscope), pictures (television, computer monitor), radar targets and others.
The CRT uses an evacuated glass envelope which is large, deep, heavy, and relatively fragile.
(http://en.wikipedia.org/wiki/Cathode_ray_tube)

CD Rom-A CD-ROM (pronounced /ˌsiːˌdiːˈrɒm/, an acronym of "Compact Disc Read-only memory") is a pre-pressed compact disc that contains data accessible to, but not writable by, a computer for data storage and music playback. The 1985 “Yellow Book” standard developed by Sony and Philips adapted the format to hold any form of binary data.
(http://en.wikipedia.org/wiki/CD-ROM)

RAM-(random access memory) is the place in a computer where the operating system, application programs, and data in current use are kept so that they can be quickly reached by the computer's processor. RAM is much faster to read from and write to than the other kinds of storage in a computer, the hard disk, floppy disk, and CD-ROM. However, the data in RAM stays there only as long as your computer is running. When you turn the computer off, RAM loses its data. When you turn your computer on again, your operating system and other files are once again loaded into RAM, usually from your hard disk.)
(http://searchmobilecomputing.techtarget.com/definition/RAM)

ICT-Information and communications technology or information and communication technology,[1] usually called ICT, is often used as an extended synonym for information technology (IT) but is usually a more general term that stresses the role of unified communications and the integration of telecommunications (telephone lines and wireless signals), intelligent building management systems and audio-visual systems in modern information technology.
(http://en.wikipedia.org/wiki/Information_and_communications_technology)

CPU-“Central Processing Unit”, is the brains of the computer. Sometimes referred to simply as the processor or central processor, the CPU is where most calculations take place. In terms of computing power, the CPU is the most important element of a computer system. On large machines, CPUs require one or more printed circuit boards. On personal computers and small workstations, the CPU is housed in a single chip called a microprocessor.
(http://www.birds-eye.net/definition/c/cpu-central_processing_unit.shtml)

"LED" A light-emitting diode (LED) is a semiconductor light source. LEDs are used as indicator lamps in many devices, and are increasingly used for lighting. Introduced as a practical electronic component in 1962, early LEDs emitted low-intensity red light, but modern versions are available across the visible, ultraviolet and infrared wavelengths, with very high brightness.
(http://en.wikipedia.org/wiki/LED )